From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6552A2F5489 for ; Wed, 16 Jul 2025 15:50:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752681051; cv=none; b=BGd0qNUTH0mQExNJppx8yrE7Ryc/Fhqf9yqnQkMy8yCfxQi8GrALpjz4b/9TBp6ddRgWjB989r338PKnUnaTb7KV9fKB/j9SOp97ImebCV6EPtn0m4i+lV07+ladMhIPp5DcXumLa3ZMT5dftQ+8X6iswCggOUXoFDASDvCrKUI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752681051; c=relaxed/simple; bh=LIQP3cOp66BC2+/dgQkvdO4IC8KgHUx4PxVZbqMt6ZU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cpRxIwGfvcTSAz1/uVsupxiDL3r7QzqsA4y6WBLLF5te8kpZDaj0A/U4hydEgqrN8iMZnWuvkaf4tJLfP7tl4ZqZvJXB1Kn6OFWd6l2n/35bX0Sj0vk9umA08wSCs1baU+nQPm8IVpWpC1pyTOzfEqvD0ZgypnfJmRpTJ5KwEp4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eYqAaikd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eYqAaikd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1CACC4CEF0; Wed, 16 Jul 2025 15:50:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752681051; bh=LIQP3cOp66BC2+/dgQkvdO4IC8KgHUx4PxVZbqMt6ZU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eYqAaikd4MfJgFYZ/Awc0CAQF+FUX06vdHAX4P6gLfys86dThR6GRvPIyNgYG8PYW Oeq7GtxUfU2Duw4X71R3DCw/D6IK+h7723dh9G64Pl8TTX9zjop2LuF+YVE5BIQbzZ rul4cTzT0IpDTg+ANzUzdNKzYkkfNjc9bS+PD4AIniXYEsSa9zLE03R+ueEsk9wi2a +5GPM8kAQcVv87VuvB7HfGmnbW/tiGda4ns6Bz+ukGxupUE98NrMnXjdGIJVifJQh7 JCmBmsVYcfQa2VW2JKMTPobal3raYqFJh+QmAP1KsjlUvsq58rvsWEi4iKpdD9Vf5z YdEA9zLHnqqkA== Date: Wed, 16 Jul 2025 08:50:49 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: Carlos Maiolino , Hans Holmberg , linux-xfs@vger.kernel.org Subject: Re: [PATCH 1/7] xfs: don't allocate the xfs_extent_busy structure for zoned RTGs Message-ID: <20250716155049.GH2672049@frogsfrogsfrogs> References: <20250716125413.2148420-1-hch@lst.de> <20250716125413.2148420-2-hch@lst.de> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250716125413.2148420-2-hch@lst.de> On Wed, Jul 16, 2025 at 02:54:01PM +0200, Christoph Hellwig wrote: > Busy extent tracking is primarily used to ensure that freed blocks are > not reused for data allocations before the transaction that deleted them > has been committed to stable storage, and secondarily to drive online > discard. None of the use cases applies to zoned RTGs, as the zoned > allocator can't overwrite blocks before resetting the zone, which already > flushes out all transactions touching the RTGs. > > So the busy extent tracking is not needed for zoned RTGs, and also not > called for zoned RTGs. But somehow the code to skip allocating and > freeing the structure got lost during the zoned XFS upstreaming process. > This not only causes these structures to unessecarily allocated, but can nit: unnecessarily > also lead to memory leaks as the xg_busy_extents pointer in the > xfs_group structure is overlayed with the pointer for the linked list > of to be reset zones. > > Stop allocating and freeing the structure to not pointlessly allocate > memory which is then leaked when the zone is reset. Yikes! Cc: # v6.15 > Fixes: 080d01c41d44 ("xfs: implement zoned garbage collection") > Signed-off-by: Christoph Hellwig With those added, Reviewed-by: "Darrick J. Wong" --D > --- > fs/xfs/libxfs/xfs_group.c | 14 +++++++++----- > fs/xfs/xfs_extent_busy.h | 8 ++++++++ > 2 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_group.c b/fs/xfs/libxfs/xfs_group.c > index e9d76bcdc820..20ad7c309489 100644 > --- a/fs/xfs/libxfs/xfs_group.c > +++ b/fs/xfs/libxfs/xfs_group.c > @@ -163,7 +163,8 @@ xfs_group_free( > > xfs_defer_drain_free(&xg->xg_intents_drain); > #ifdef __KERNEL__ > - kfree(xg->xg_busy_extents); > + if (xfs_group_has_extent_busy(xg->xg_mount, xg->xg_type)) > + kfree(xg->xg_busy_extents); > #endif > > if (uninit) > @@ -189,9 +190,11 @@ xfs_group_insert( > xg->xg_type = type; > > #ifdef __KERNEL__ > - xg->xg_busy_extents = xfs_extent_busy_alloc(); > - if (!xg->xg_busy_extents) > - return -ENOMEM; > + if (xfs_group_has_extent_busy(mp, type)) { > + xg->xg_busy_extents = xfs_extent_busy_alloc(); > + if (!xg->xg_busy_extents) > + return -ENOMEM; > + } > spin_lock_init(&xg->xg_state_lock); > xfs_hooks_init(&xg->xg_rmap_update_hooks); > #endif > @@ -210,7 +213,8 @@ xfs_group_insert( > out_drain: > xfs_defer_drain_free(&xg->xg_intents_drain); > #ifdef __KERNEL__ > - kfree(xg->xg_busy_extents); > + if (xfs_group_has_extent_busy(xg->xg_mount, xg->xg_type)) > + kfree(xg->xg_busy_extents); > #endif > return error; > } > diff --git a/fs/xfs/xfs_extent_busy.h b/fs/xfs/xfs_extent_busy.h > index f069b04e8ea1..3e6e019b6146 100644 > --- a/fs/xfs/xfs_extent_busy.h > +++ b/fs/xfs/xfs_extent_busy.h > @@ -68,4 +68,12 @@ static inline void xfs_extent_busy_sort(struct list_head *list) > list_sort(NULL, list, xfs_extent_busy_ag_cmp); > } > > +/* > + * Zoned RTGs don't need to track busy extents, as the actual block freeing only > + * happens by a zone reset, which forces out all transactions that touched the > + * to be reset zone first. > + */ > +#define xfs_group_has_extent_busy(mp, type) \ > + ((type) == XG_TYPE_AG || !xfs_has_zoned((mp))) > + > #endif /* __XFS_EXTENT_BUSY_H__ */ > -- > 2.47.2 > >